1. Field of the Invention
The present invention pertains to a keyboard key with a touch surface on a mobile part of the key, which surface is large compared with an electrical contact to be actuated, and with a guiding means which guides the mobile part of the key relative to an immobile part of the key, wherein the guiding means is linked with the mobile part on the one hand, and with the immobile part of the key, on the other hand, and the guiding means transmits a touch force exercised on an edge zone of the touch surface to an opposite edge zone of the mobile part of the key.
2. Description of the Prior Art
The general type of key with respect to which this invention provides an improvement is, for example, the "space" key of a typewriter keyboard. In such a key, which is long but narrow, the guiding means is formed by a swivel bow which is linked to both ends of the key. When pressed at one end of the key, it carries the other end of the key, so that the switching of the electrical contact is practically independent of the point at which the key is pressed. In addition to this type of key, large keys are also often provided in the case of typewriter keyboards as well as input and output keyboards of terminals, which large keys cover a large surface which is several times the size of the prevailing key size. It must be ensured in the case of such keys that when the key is pressed the corresponding switching contact is always actuated in the same manner, regardless of which part of the key is being pressed. In addition, there should be no tendency to jam. Keys of the general type described above often have no return spring members of their own. They are often brought into their home position by a resetting spring which also replaces the corresponding electrical contact. For example, rubber membranes are provided for this purpose. In the case of large-area keys of this type it must be ensured that the key returns to its home position safely, even if no resetting spring is provided and the resetting force of the contact assembly is weak and does not act in a central area of the key.